Small bore pipe, for example having an inner diameter of about 3 inches (about 76 mm) or less, is used extensively as process pipework in a variety of industries, including the oil and gas, pharmaceutical, manufacturing and utility industries.
At various points during the installation, working life or decommissioning of any pipe, it may be necessary to isolate a section of the pipe for repair, replacement or to perform an operation in the pipe.
Typically, pipe isolation in large bore pipe may be carried out by inserting a tool into the pipe bore to either block the pipe bore or surround a region of the pipe wall.
However, isolating small bore pipe offers several isolation challenges compared to larger bore pipe.
Firstly, mechanical tooling presently available for large bore pipe does not easily scale down for use in small bore pipe. Furthermore, as noted above small bore pipe is often used in process pipework where access for the installation of isolation devices is restricted or limited.
A number of systems for isolating small bore pipe, such as gel products and freeze plugs, have been proposed. However, these proposed solutions are only suitable for relatively low pressure or ambient isolations. Although some mechanical systems have been developed for straight and open access pipework, including some hot tap installed isolation tools with welded fittings, existing mechanical systems require access for welding equipment and also that the pipe be severed inside the fitting, which may not be desirable or practical in many applications.